JPH02208704A - I/o bus extension device of programmable controller - Google Patents

Abstract

PURPOSE:To execute a long distance transmission by using a balance transmission system being immune to noise between an unbalance/balance conversion unit of a fundamental base part and an unbalance/balance conversion unit of each extended base part. CONSTITUTION:In the case of transferring the data to an extended base 2 from a fundamental base 1, a data signal and various control signals on an I/O bus of the fundamental base 1 are sent out onto a data bus 32 and onto an output signal line 16a of a control bus through an I/O bus connecting connector 11. Subsequently, when a gate control circuit 20 generates a gate enable signal to a line driver 14 and a line driver 17, these data signals and control signals are converted to differential signals from single signals, respectively, and sent to a connector 7. Therefore, on an I/O extension cable 8 for connecting the fundamental base 1 and the extended base 2, these data signals and control signals are transmitted in parallel by a balance transmission system. In such a way, a long distance and high speed transmission can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an I/O bus expansion device that connects a basic base and an extension base in a programmable controller with a bus line.

[Conventional technology]

A programmable controller has a control unit and a power supply unit mounted on a basic base, and an I/O unit is mounted when necessary.

This I/O unit is an interface for connecting an external device to be controlled to the I/O bus inside the basic base.

By the way, since there are many devices to be controlled, I
If there are not enough /O units to be installed, or if you are trying to operate a controlled device in a remote location, install the I/O unit that will interface with that device on a separate expansion base from the basic base. The I/O bus of this basic base and the expansion base will be connected.

Therefore, in the past, PWB [printed wiring
board] or via cable. Furthermore, when operating equipment at a remote location, I/O buses are connected using a serial transmission method via a communication unit built into the CPU.

[Problem to be solved by the invention]

However, since the unbalanced transmission method uses a single signal line, it is susceptible to noise, and generally, when handling high-speed signals of several hundred kHz or more, such as in a programmable controller, transmission is limited to a distance of several meters.

Therefore, if the I/O buses of the basic base and expansion base are connected using the conventional unbalanced transmission method, a problem arises in that it is not possible to operate the controlled equipment installed at a remote location. .

Furthermore, when the basic base and the expansion base are connected using a serial transmission method, a time delay occurs due to parallel-to-serial conversion of signals in the communication unit and processing based on a predetermined communication protocol.

Therefore, in this case, complete real-time remote I/O control of the controlled device becomes difficult, and
A problem has arisen in that a communication unit with a built-in CPU becomes expensive.

[Means to solve the problem]

In order to solve the above-mentioned problem, the I/O bus expansion device for a programmable controller according to the present invention has a problem in the basic base part on which the control part is mounted and the extension base part in which the expansion I/O part is mounted. For a balanced I/O bus, the single signal on each bus line is converted to a differential signal and output to the differential signal line, and the differential signal on each differential signal line is converted to a single signal and output to the I/O bus. The unbalanced/balanced conversion units output to the /O bus are connected to the differential signal lines of the unbalanced/balanced conversion units in the basic base section and the differential signals of the unbalanced/balanced conversion units in each extension base section. It is characterized by the fact that the lines are connected to each other.

[For production]

In the basic base unit and each expansion base unit, an unbalanced/balanced conversion unit converts each single signal line on the I/O bus side through a line driver, a line receiver, or both, depending on the input/output direction. Connected to the differential signal line. The differential signal lines of the unbalanced/balanced conversion unit in the basic base section and the differential signal lines of the unbalanced/balanced conversion units in each extension base section are connected to each other. Then, each single signal on the I/O bus is once converted into a differential signal by one unbalanced/balanced conversion unit, and then transmitted to the other unbalanced/balanced conversion unit via each differential signal line. Ru. The other unbalanced/balanced conversion unit converts the differential signal back into a single signal and outputs it to the I/O bus. Therefore, the unbalanced/balanced conversion unit in the basic base section and the unbalanced/balanced conversion unit in the expansion base section are connected by the balanced transmission method. Since the signal is converted into a differential signal and transmitted, noise added to the differential signal line in the same phase can be easily removed. Therefore, by connecting the basic base section and the extension base section using this balanced transmission method, long-distance high-speed transmission becomes possible.

Furthermore, since the I/O buses of the basic base section and each expansion base section are connected in parallel, there is no time delay unlike in the case of a serial transmission method.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 to 3.

FIG. 3 shows the state of connection between the basic base 1 and the extension bases 2, 2 in the programmable controller of this embodiment.

Each extension base 2 is equipped with a power supply unit 3 and a plurality of I/O units 4 . The power supply unit 3 is
This is a device for supplying power to each unit in the extension base 2. Each I/O unit 4 has an I/O unit inside the expansion base 2.
/O bus. And each of these I/
The O unit 4 serves as an interface with the I/O bus by being connected to an external controlled device (not shown).

On the basic base 1, a power supply unit 3 similar to the expansion base 2, a plurality of I/O units 4, and a control unit 5 are mounted. Each I/O unit 4 and control unit 5 is connected to the basic base 1.
are connected via an I/O bus within the This control unit 5 has an internal CPU, and controls the basic base 1 and the expansion bases 2 and 2 based on the sequence program.
This is a device that performs input/output control of the I/O units 4 installed in the. Therefore, the basic base 1 side on which this control unit 5 is mounted becomes the basic base part of the programmable controller, and the I/O unit 4 for expansion...
・The extension base 2/2 side where is mounted becomes the extension base part.

I/O bus expansion units 6 are mounted on the basic base 1 and the expansion bases 2, 2, respectively. Each I/O bus expansion unit 6 is connected to the /O bus within the installed basic base 1 or expansion base 2. Furthermore, each I/O bus expansion unit 6 is provided with two connectors 7. And each I/O
By connecting the connectors 7 provided on the bus expansion unit 6 with the I/O extension cables 8, the basic base 1 and each extension base 2 are connected. Note that each signal line is directly connected between the two connectors 7 and 7 on the I/O bus expansion unit 6, as will be explained later, so when one expansion base is connected to the basic base 1, 2, the other extension base 2 is also connected to the basic base 1.

The internal configuration of the I/O bus expansion unit 6 mounted on the basic base 1 will be explained based on FIG. 1.

The I/O bus of the basic base 1 is connected to the I/O bus connection connector 11 of the I/O bus expansion unit 6.

Inside the I/O bus expansion unit 6, the data bus 12 from the I/O bus connector 11 is connected to the connectors 7 and the termination connector 13 via a line driver 14 and a line receiver 15. It is connected.

Since the data bus 12 performs bidirectional transmission, it requires a line driver 14 and a line receiver 15 connected in parallel. The line driver 14 consists of a plurality of drivers having differential outputs, each driver converting each single signal on the bus line into a differential signal. Further, the line receiver 15 includes a plurality of receivers having differential inputs, and each receiver converts each differential signal into a single signal. Therefore, the data bus 12 includes a line driver 14 and a line receiver 15.
Therefore, on the I/O bus connector 11 side, each bus line is composed of a single signal line, and on the connector 7 side, it is composed of differential signal lines.

The control bus from the I/O bus connector 11 is connected to the output signal line 16a to the extension base 2 side and the basic base 1.
and an input signal line 16b. Each output signal line 16a of this control bus is connected to the connectors 7 and the terminal connector 13 via a line driver 17. In addition, each input signal line 16b of the control bus is connected via a line receiver 18 to
They are connected to the same connectors 7, 7 and the terminal connector 13. This line driver 17 and line receiver 18
These also have the same configuration as the line driver 14 and line receiver 15, respectively.

The control bus is composed of a single signal line and a differential signal line on the left and right sides of the line driver 17 and line receiver 18, respectively.

The PC bus 19 from the I/O bus connector 11 is connected to the connectors 7, 7. connected directly to. This PC bus 1
Reference numeral 9 is a signal line for peripheral tools such as a programmer in the programmable controller, and since it has already become a serial communication line for balanced transmission method by the unbalanced/balanced conversion unit installed in the control unit 5, it can be connected to the connector as it is. It will be connected to 7.7.

Each line driver 14, 17 and line receiver 15,
The gate control output of the gate control circuit 20 is connected to the gate enable signal input 18. The gate control circuit 20 is a programmable semi-custom gate circuit that decodes signals on the control bus and outputs gate enable signals from respective gate control outputs. Note that the LED 21 connected to this gate control circuit 20 is connected to the I/O when it is operating normally.
This is a monitor LED that lights up on the panel surface of the O bus expansion unit 6.

One ends of the I/O extension cables 8, 8 are connected to the connectors 7, 7, respectively, as described above. Each I/O extension cable 8 is a balanced transmission type signal line that includes a plurality of differential signal lines. The termination connector 13 has a termination resistor (470Ω) when this I/O bus expansion unit 6 becomes a termination station.
It is a connector for connecting. Note that this terminal connector 13 is omitted from illustration in FIG. 3. Also, I
The power line 22 of the /O bus connector 11 is not shown, but! It is connected to the internal circuit of the /O bus expansion unit 6 and the connectors 7.

Next, the internal configuration of the I/O bus expansion unit 6 mounted on the expansion base 2 will be explained based on FIG. 2.

The I/O bus of the extension base 2 is connected to the I/O bus connection connector 31 of the I/O bus expansion unit 6.

Inside the I/O bus expansion unit 6, the data bus 32 from this I/O bus connection connector 31 is connected to the connector 7.
7 and the terminal connector 33, the line driver 34
and a line receiver 35. This allows the data bus 32 to perform bidirectional transmission as in the case of FIG. 1. The line driver 34 and line receiver 35 have the same configuration as the line driver 14 and line receiver 15 shown in FIG. 1, respectively. The data bus 32 is composed of a single signal line and a differential signal line on the left and right sides of the line driver 34 and line receiver 35, respectively.

The control bus from the I/O bus connector 31 connects the output signal line 37a to the basic base 1 side and the expansion base 2.
and an input signal line 37b. Each output signal line 37a of this control bus is connected to the connectors 7 and the terminal connector 33 via a line driver 38. In addition, each input signal 1i37b of the control bus is transmitted via the line receiver 39.
They are connected to the same connectors 7, 7 and the terminal connector 13. The above line driver 38 and line receiver 39
The line driver 14 and the line receiver 15 have the same configuration as shown in FIG. 1, respectively. The control bus is composed of a single signal line and a differential signal line on the left and right sides of the line driver 38 and line receiver 39, respectively.

The PG bus 1 from the I/O bus connector 31 is directly connected to the connectors 7 as in the case of FIG. 1 above. The PG bus 1 is also directly connected to the programmer connector 42 and the termination connector 33. The programmer connector 42 is a connector for connecting a programmer (not shown).

Each line driver 34, 38 and line receiver 38,
The gate control output of the gate control power supply down detection circuit 43 is connected to the gate enable signal input of 39. Like the gate control circuit 20 shown in FIG. 1, the gate control circuit 43 decodes signals on the control bus and outputs gate enable signals from respective gate control outputs. The gate control circuit 43 also has a function of detecting an abnormality in the power supply unit 3 mounted on the extension base 2. Further, the gate control circuit 43 and the I/O bus connection connector 31 are connected by a rack number bus 44, and a rack number setting switch 45 is connected to the rack number bus 44. This rack number setting switch 45 allows the control unit 5 of the basic base 1 to be set to the number of the expansion base 2 by setting the rack number setting switch 45 from the expansion base 2 side. /O unit 4... is used to set an address when accessing. Therefore, when the gate control circuit 43 outputs the gate enable signal, it also refers to the setting value of the rack number setting switch 45. Note that L connected to this gate control circuit 43
The ED 46 is a monitor LED that lights up on the panel surface of the I/O bus expansion unit 6 when it is operating normally.

The connectors 7 and 7 have an I/O expansion cable 8 for connecting to the other end of the I/O expansion cable 8 shown in FIG. 1 or to the I/O bus expansion unit 6 mounted on another expansion base 2.
One end of each is connected. The terminating connector 33 is a connector for connecting a terminating resistor when this I/O bus expansion unit 6 serves as a terminating station, as in the case of FIG.

Note that the terminal connector 33 and the programmer connector 42 are not shown in FIG. 3. Also, I/
Although not shown, the power line 47 of the O bus connector 31 is also connected to the internal circuit of the I/O bus expansion unit 6 and the connectors 7.

The operation of the I/O bus expansion unit 6 having the above configuration will be explained.

When transferring data from the basic base 1 to the expansion base 2, the data signals and various control signals on the I/O bus of the basic base 1 are transferred to the data bus 32 and the control bus via the I/O bus connector 11. It is sent onto the output signal line 16a. Then, when the gate control circuit 20 issues a gate enable signal to the line driver 14 and the line driver 17, these data signals and control signals are each converted from a single signal to a differential signal and sent to the connector 7. For this reason, the basic base 1
These data signals and control signals are transmitted in parallel on the I/O extension cable 8 that connects the extension base 2 and the extension base 2 using a balanced transmission method.

In the I/O bus expansion unit 6 of the expansion base 2, these data signals and control signals are sent via the connector 7 onto the data bus 32 and onto the input signal line 37b of the control bus.

Then, when the gate control circuit 43 issues a gate enable signal to the line receiver 35 and the line receiver 39, these data signals and control signals are respectively converted from differential signals to single signals and sent to the I/O bus connector 31. Sent.

Therefore, the data signal and control signal are again sent to the I/O bus of the extension base 2 as unbalanced signals.

At this time, the control signal emitted from the extension base 2 side is converted into a balanced signal by the line driver 38, and sent to the line receiver 18 on the basic base l side via the I/O extension cable 8, where it is converted into an unbalanced signal again. is sent to the I/O bus as

Also, when data is transferred from the extension base 2 to the basic base 1, data is transmitted in parallel on the I/O extension cable 8 using the balanced transmission method in the same manner as described above.

As a result, each signal is transmitted on the I/O extension cable 8 as a differential signal with opposite phases to each other, making it easy to remove noise on the receiving side and enabling long-distance transmission. Incidentally, in the case of this embodiment, transmission over a total length of approximately 200 m is possible.

In addition, since the basic base l and the expansion base 2 are connected in parallel via the I/O expansion cable 8, there is no time delay that occurs when using the serial transmission method, and the control unit on the basic base l 5 enables real-time remote I/O control of the controlled equipment connected to the I/O unit 4 on the extension base 2.

〔Effect of the invention〕

As described above, the I/O bus expansion device for a programmable controller according to the present invention has an unbalanced type structure between the basic base section on which the control section is mounted and the extension base section on which the expansion I/O section is mounted. The single signal on each bus line is converted to a differential signal and output to the differential signal line, and the differential signal on each differential signal line is converted to a single signal and output to the I/O bus.
The unbalanced/balanced conversion units that output to the bus are connected, and the differential signal lines of the unbalanced/balanced conversion units in the basic base section and the differential signal lines of the unbalanced/balanced conversion units in each extension base section are connected. It has a specific configuration.

As a result, a balanced transmission system that is resistant to noise can be established between the unbalanced/balanced conversion unit of the basic base part and the unbalanced/balanced conversion unit of each extension base part, so that long-distance transmission is possible. Further, since the I/O bus of the basic base section and the I/O bus of each expansion base section are connected in parallel, there is no time delay unlike in the case of a serial transmission method.

Therefore, according to the present invention, it is possible to perform real-time remote I/O control without time delay on a controlled device installed at a location away from the basic base unit.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention, in which Figure 1 is a block diagram of an I/O bus expansion unit mounted on a basic base, and Figure 2 is a block diagram of an I/O bus expansion unit mounted on an expansion base. I/
FIG. 3, a block diagram of the O bus expansion unit, is a perspective view of a programmable controller in which a basic base and an extension base are connected via an I/O bus expansion unit. 1 is the basic base, 2 is the expansion base, 4 is the I/O unit (I/O section), 5 is the control unit (control section), 6 is the I/O bus expansion unit (unbalanced/balanced conversion unit), 8 is I/O expansion cable (differential signal line)
It is.

Claims (1)

[Claims] 1. Convert the single signal of each bus line into a differential signal on the unbalanced I/O bus between the basic base unit where the control unit is mounted and the expansion base unit where the expansion I/O unit is mounted. An unbalanced/unbalanced signal that converts the differential signal on each differential signal line into a single signal and outputs it to the I/O bus.
The balanced conversion units are connected to each other, and the differential signal lines of the unbalanced/balanced conversion units in the basic base part and the differential signal lines of the unbalanced/balanced conversion units in each extension base part are connected to each other. I/O bus expansion device for programmable controllers.